Electrical transmission of intelligence



C. D. EHRET.

ELECTRICAL TRANSMISSION OF INTELLIGENCE.

APPLICATION FILED MAR. 26. 1919.

1 ,352,589, PatentedSept. 14, 1920.

UNITED STATES CORNELIUS I). EHBET, 0F PHILADELPHIA, PENNSYLVANIA.

ELECTRICAL TRANSMISSION OF INTELLIGENCE.

Specification of Letters Patent. Patented Sept. 14, 1920.

Application filed March 26, 1919. Serial No. 285,164.

To all whom it may concern:

Be it known that I, CORNELIUS D. EHRET, a citizen of the United States, residing in the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Electrical Transmission of Intelligence, of which the following is a specification.

My invention relates to the electrical transmission of intelligence, more particularly the transmission of telegraphic or other signals or messages, in either radio or conduction systems, the signals or messages being represented in transmission by oscillatory or carrier wave energy.

y invention resides in a method and ap paratus for electrically transmitting intelligence characterized by the fact that a pluralityof signals or messages may be simultaneously transmitted, elements or components of the different messages or signals being alternately transmitted, whereby there is no interference or confusion among them.

My invention resides in a method and apparatus of the character referred to wherein thermionic means are employed for producing oscillations in alternating groups representing elements or components of different signals or messages, the energy for the different groups of oscillations, which may have different frequencies, being supplied from the same or different sources.

My invention resides in a system of the character hereinafter described.

For an understanding of my method and for an illustration of some of the various forms of apparatus embodying my invention, reference is to be had to the accompanying drawing, in which:

Figure 1 is a diagrammatic view of apparatus for simultaneously transmitting without interference a plurality of telegraphic signals. 1

Fig. 1 is a diagrammatic view of a modification of part of Fig. 1.

Fig. 2 is a diagrammatic view of a modified form of apparatus.

Fig. 2 is a diagrammatic View of a modification of part of Fig. 2.

Fig. 3 is a diagrammatic view of a further modification of my apparatus.

Fig. 4 is a diagrammatic view of one of many va u forms of r c iv g appa which may be used incooperation with the transmitting ap aratus.

Referring to ig. 1, G is a source or generator of any type or character producing fluctuating or alternating current, of any desired or suitable frequency, including a frequency which will produce at thereceiving station a note of approximately 1000 vibrations per second, or any other suitable or desired pitch, even above audibility, in which case heterodyne or beatreception may be employed. The primaries of the transformers t and t ma be separately energized from the source through the signaling instruments, as keys is and k.

V is a thermionic device having the anodes or plates 32 p grid 9 and electron-emitting body or incandescent filament f heated by current from the battery I). A condenser C is connected in circuit with the secondary of the transformer 25, and is also included in the circuit of the anode or plate p including an adjustable part of the inductance L. Similarly, in circuit with the secondary of the transformer t is a con denser C in the circuit of the plate with a variable portion of the inductance By the inductance d the circuit of the grid 9 1s coupled to both plate circuits. If desired or suitable, there may be employed in the grid circuit a condenser c or in lieu of it a battery, in well known manner.

Each of the plate circuits is oscillatory, the natural period being variable either by adjusting the amount of the inductance L employed, or by varying the capacities of the condensers C and-C, their capacities being preferably independently variable.

The inductance L may communicate resulting oscillations either to a radiating structure R, between which and earth E the inductance L may be connected, or any other suitable radiating structure or equivalent for impressing upon the natural mediaenergy of the high frequency oscillations. Or the inductance L may impress energy of the oscillations upon a wire or conducting system extending between transmitting and receiving stations, as in line wire carrier wave systems.

With the plate circuits having different natural periods, the oscillations produced in them will have different fre uencies. The radiating structure or path, E

may be attuned to either of these frequencies. but is preferably attuned to a frequency midway between them. so that equal amounts of energy will be radiated from oscillations of the two different freqnencies.

There may be. an operator for each of the keys M, if. Each manipulates his key independently of the other in iu-cordance with the signals or intelligence to be transmitted. But in the circuit of the plate there will be produced oscillations. due to the asymmetric conductivity of that circuit, only from energy of the half cycles or waves of one polarity or sign of the source G; similarly, from energy of the waves or half cycles of opposite sign oscillations will be produced in the circuit of plate p oscillations being produced in the two plate circuits alternately. that is. one plate circuit will oscillate during a half cycle of the source G and then become inactive, but during its inactivity the other plate circuit will oscillate. This is readily accomplished by winding the transformer coils or so connecting them that while the upper terminal of the transformer z is. for example. positive. the lower terminal of the transformer f will be negative.

Accordingly, there will be transmitted alternately groups of oscillations of different frequencies. each frequency representing different signals. The oscillations of different frequencies may be received at separate receiving stations or at the same station.

In Fig. 4: are indicated simple receiving circuits of known form. which may be located at one and the same station. or at widely difierent stations. Each receiving apparatus comprises an absorbing structure, as antenna A or any equivalent. between which and earth E is connected the adjustable inductance or oscillation transformer primary L The circuit of the transformer secondary L is tuned by the variable condenser C to one terminal of which may be connected the grid of the thermionic detector o1 amplifier Y in the circuit between whose plate and filament 7" is a source of energy or battery B and. the winding T which may be that of a receiving telephone or the primary of a transformer which may deliver energy to a succeeding circuit or circuits for cascade amplification or other purposes. There is a similar arrangement comprising the absorbing system .V, inductance L. with tuned secondary circuit L C in association with the thermionic detector or amplifier V whose grid is connected to one terminal of the condenser C and in the circuit between whose plate or anode p and filament 7' is a battery B aml winding T" of a telephoi'ie or primary of a transforn'ier for purposis similar to those of winding T.

The receiving apparatus associated with the absorber may be attuned to the frequency, for example, of the oscillations resulting in the radiating structure R of Fig. 1 due to the circuit of the plate 7) of the thermionic oscillator V; and similarly, the receiving circuits associated with the absorbing system A may be attuned to the energy result ing from oscillations in the circuit of the plate p of the oscillator V, Fig. 1. There fore, whether the receiving apparatus be at the same or different stations, two messages may be simultaneously transmitted by the apparatus of Fig. 1 and received without interference at the same receiving station or different receiving stations.

It will of course be understood that in Fig. 4 is illustrated merely one of many forms of receiving apparatus at one or different stations that may be employed, those skilled in this art readily employing various equivalents.

In Fig. 2 the transmitting apparatus is similar to that of Fig. 1, except that two sources G and G of alternating or fluctuaing current are provided. each in association respectively, with the transformers t and t In this case the operation is in general the same as in Fig. 1, except that in the case of Fig. 2 the sources G and Gr may deliver currents of different frequencies. with resultant different notes at the receiving apparatus; or currents of different frequencies above audibility for cooperation with beat or heterodyne receivers; or currents one of which is of inaudible and the other audible frequency. The plate circuits and may produce oscillations of the same frequency or different frequencies, 'n'eferably, however, different frequencies. It will be understood further that while the sources G and G preferably deliver cur rent of different frequencies, they may deliver currents of the same frequency, which may be in such phase relation with respect to each other as to cause the groups of oscillations in the two plate circuits to alternate, or to cause groups of oscillations which overlap each other in time. When they do so overlap each other in time, the fact that they are of different frequencies will assist in assuring non-interference between the different signals, as effected by the different keys and 70 'hile in both Figs. 1 and 2 the same radiating or aerial structure It is employed, separate radiating structures may be employed, as indicated in Fig. 3. In this case, the primaries of the transformers t and t may be related to a single source as G of Fig. l, as therein indicated, or with separate sources (i and (i as indicated in Fig. 2. \Vith each plate 12 p of the oscillator V of Fig. 3 may be associated, respectively, the grids The circuit of the plate p includes an adjustable oscillation primary L whose adjustable secondary L is connected through a variable inductance L with the radiator R Similarly, the circuit of the plate p includes a separate inductance L whose secondary L connects through a variable inductance L with the radiator R". The respective grid circuits, which may include condensers of batteries 0 0 are inductively related through inductances d and (1*, respectively, with the inductances L and L.

It is understood that the apparatus as described in connection with Fig. 4, or any equivalent apparatus, either at the same or different stations, will cooperate with the .apparatus shown in Figs. 2 and in substantially the same manner as described 111 connection with Fig. 1.

lVhen, as above referred to, the transmitted waves do not have an audible group frequency, as for telegraphy, beat or heterodyne reception at the receiving station or stations, may be resorted to. For this purpose, as indicated in Fig. 4, oscillations may be locally produced, in case hete-rodyne reception is desired, but to which my invention is not limited, in any well known manner, as for example, by the sources 8 and s inductively coupled, respectively, with the receiving apparatus. The frequency of each of these local sources of oscillations is made such that the difference between the received frequency and the frequency of the local source Wlll produce beats of any desired frequency, as for example, an audible freuency.

It will further be understood as to Fig. 1, that the source G and keys is, k may be supplanted, respectively, as indicated in Fig. 1 by a battery 6 or source of. direct current and microphones m, 112.. And in Fig. 2 the sources G G may be supplanted by sources of direct current, as batteries 6 b and thekeys I2 and k supplanted by microphones m, m as indicated in Fig. 2. Or with each of the microphones referred to may be employed a source of fluctuating or alternating current, in lieu of the associated battery or source of direct current, of freuency above audibility. For example, in Big. 1, the source b may deliver fluctuating or alternating current of frequency above audibility.

.lVith such changes, a plurality of telephonic messages may be transmitted from the same station without interference, each telephonic message having therein gaps of very short duration, the gaps in the two messages alternating, as in the case of telegraphy above described.

Vhile the oscillators V in Figs. 1, 2 and 3 are shown as comprising anode circuits having thermionic paths within one and the same evacuated vessel, it will be understood that my invention is not so limited, but

that the thermionic )aths may be disposed in separate evacuated vessels, in which case a grid and filament will be associated with each anode or plate.

\Vhat I claim is:

l. The method of simultaneously transmitting a plurality of signals or messages without interference, which consists in impressing alternating current upon a plurality of asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations, controlling the energy producing each group of oscillations in accordance with a signal or message, and impressing energy of the oscillations of the alternating groups upon a transmitting medium.

2. The method of simultaneously trans mitting a plurality of signals or messages without interference, which consists in impressing alternating current upon a plurality of asymmetrically conducting oscillation-producing thermionic paths to pro duce alternating groups of oscillations, controlling the energy producing each group of oscillations in accordance wit-h a signal or message, impressing energy of the oscillations of the alternating groups upon a transmitting medium, and selectively receiving the energy of the different groups of oscillations.

3. The method of simultaneously transmitting a plurality of signals or messages without interference, which consists in impressing alternating current upon a plurality of asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations of different frequencies, controlling the energy producing each group of oscillations in accordance with a signal or message, and impressing energy of the oscillations of the alternating groups upon a transmitting medium.

4. The method of simultaneously transmitting a plurality of signals or messages without interference, which consists 1n im-- pressing alternating current upon a plurality of asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations of different frequencies, controlling the energy producing each group of oscillations in accordance with a signal or message, impressing energy of the oscillations of the alternating groups upon a transmitting medium, and selectively receiving the energy of the diflerent groups of oscillations.

5.'The method of simultaneously transmitting without interference a plurality of signals or'messages, which consists in alternately supplying electrical energy to asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations, controlling the energy delivered to each of said paths in accordance with a signal or message, and

impressing energy of the oscillations of the different groups upon a transmitting me dium.

6. The method of simultaneously transmitting without interference a plurality of signals or messages, which consists in alternately supplying electrical energy to asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations of different frequencies, controlling the energy delivered to each of said paths in accordance with a signal or message, and impressing energy of the oscillations of the different grpups upon a transmitting medium.

1. lhe method of simultaneously transmitting without interference a plurality of signals or messages, which consists in alternately supplying electrical energy to asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations, controlling the energy delivered to each of said paths in accordance with a signal or message, impressing energy of the oscillations of the different groups upon a transmitting medium, and selectively receiving the energy of the different groups of oscillations.

8. The method of simultaneously transmitting without interference a plurality of signals or messages, which consists in alternately supplying electrical energy to asymmetrically conducting oscillation-producing thermionic paths to produce alternating groups of oscillations of different frequencies, controlling the energy delivered to each of said paths in accordance with a signal or message, impressing energy of the oscillations of the different groups upon a transmitting medium, and selectively receiving the energy of the different groups of oscillations.

9. The combination with thermionic oscillation-producing means having a plurality of anode circuits, of means for supplying energy to said anode circuits, and sig naling instruments controlling the energy supplied, respectively, to the different anode circuits, said anode circuits producing alternating groups of oscillations.

10. The combination with thermionic oscillationproducing means having a plurality of anode circuits, of means for supplying energy to said anode circuits, and signaling instruments controlling the energy supplied, respectively, to the different anode circuits, said anode circuits producing alternating groups of oscillations of different frequencies.

11. The combination with a pluralityof thermionic oscillation-producing anode circuits, of means for alternately supplying energy thereto to produce alternating groups of oscillations, and signaling instruments controlling the energy supplied, respectively, to the different anode circuits.

12. The combination with thermionic oscillation-producing means having a plurality of anode circuits, of means for supplying energy to said anode circuits, signaling instruments controlling the energy supplied, respectively, to the different anode circuits, means for impressing energy of the different groups of oscillations upon a transmitting medium, and means for selectively receiving energy of the different groups of oscillations.

13. The combination with thermionic oscillation-producing means having a plurality of anode circuits, of means for supplying energy to said anode circuits, signaling instruments controlling the energy supplied, respectively, to the different anode circuits, said anode circuits producing alternating groups of oscillations of different frequencies, means for impressing energy of the different groups of oscillations upon a transmitting medium, and means for selectively receiving energy of the different groups of oscillations.

14. The combination with a plurality of thermionic oscillation-producing anode circuits, of means for alternately supplying energy thereto to produce alternating groups of oscillations, signaling instruments controlling the energy supplied, respectively, to the different anode circuits, means for impressing energy of the different groups of oscillations upon a transmitting medium, and means for selectively receiving energy of the difierent groups of oscillations.

15. The method of simultaneously transmitting a plurality of signals or messages without interference, which consists in converting the positive and negative half Waves of an alternating current into different groups of oscillations, and controlling the different groups of oscillations in accordance with different signals or messages.

16. The method of simultaneously transmitting a plurality of signals or messages without interference, which consists in converting the positive and negative half-waves of an alternating current into high frequency oscillations of different frequencies, controlling the groups of oscillations in accordance with different signals or messages,-and impressing the energy of said oscillations upon a transmitting medium.

17. The combination with oscillating circuits, of means producing positive and negative currents in predetermined sequence, said circuits receiving respectively, energy of said positive and negative currents, whereby groups of oscillations are produced in like sequence, and different devices controlling the oscillations of the different groups.

18. The combination with oscillating circuits having different periods, of means prosaid circuits respectively, positive and negative currents, and different signaling instruments controlling the different groups of oscillations.

20. Apparatus for simultaneously trans- 'mitting a plurality of signals or messages without interference, comprising a plurality of circuits producinghigh frequency oscillations of different frequencies, a source of alternating current whose positive and negative half waves are impressed, respectively, on different of said circuits, and different signaling instruments controlling the different groups of oscillations.

21. The combination. with a plurality of circuits producing oscillations of different frequencies, a source of alternating current, and diflerent signaling instruments controlling delivery of energy of positive and negative half-waves, respectively, to the different oscillation producing circuits. 22. The combination with a plurality-of thermionic oscillators, of means for delivering thereto in predetermined sequence energy of positive and negative currents, respectively, whereby groups of oscillations are produced in like sequence, and different devices controlling said oscillators.

23. The combination with a plurality of oscillators, of means for deliverin thereto in predetermined sequence energy 0 positive an negative currents, respectively, whereby groups of oscillations are produced in like sequence, and independently operable devices controlling said oscillators in accordance with sound waves.

24. The-combination with a plurality of oscillators having different periods, of means for delivering thereto in predetermined sequence. energy of positive and negative currents, respectively, whereby groups of 0s cillations of different frequencies. are produced in like sequence, and independently operable devices controlling said oscillators in accordancewith sound waves.

25. The combination with a plurality of oscillators, of means for delivering thereto in predetermined sequence energy of positive and negative currents, respectively, whereby groups of oscillations are produced in like sequence, and'independently operable devices controlling said currents in accordance with sound waves. i

26. The combination with a plurality of oscillators, of means delivering thereto energy 'of alternate positive and negative ourrent waves, respectively, the waves of'each s gn recurring .at .a frequency above audibility, and devices independently modulating in accordance with sound waves the oscillations produced by the different said oscillators.

27. The combination with a plurality of thermionic oscillators, of means delivering thereto energy of alternate positive and neg-' ative current waves, respectively, the waves of each sign recurring at a frequency above audibility, and devices independently modulating in accordance with sound waves the oscillations produced by the different said oscillators.

28. The combination with a source of alternating or fluctuating current or frequency above audibility, of asymmetrically conducting oscillation producing pathsrespectively receiving therefrom positive and negative current waves, and devices modulatin in accordance with sound waves the oscil ations produced in said paths.

29. The combination with a source of alternating or fluctuating current of frequency above audibility, of asymmetrically conducting oscillation producing paths respectively receiving therefrom positive and ne ative current waves, said paths having different periods, and devices independently'modulating in accordance with sound waves the oscillations of different frequencies.

In testimony whereof I have hereunto afiixed'my signature this 25 day of March, 1919. i 

